You have a basic grasp on the market, it is predominantly driven by 1031 exchange money and institutional players. Knowing that you have to realize that the 1031 money will out pay other participants for non-real estate reasons. Also when looking at cap rates, you need to realize that is not the entire yield to the investor and that there are other factors that influence decisions. But yes, the lack of intensive management, higher liquidity as compared to alternative investments and low credit risk make this a favorable investment choice for the participants in this market sector.
However, as noted in the following article, the tenants are looking to have both sides of the valuation issue.
Walgreens and CVS Declare War on Property Taxes